There are N cities numbered from 1 to N.
You are given connections, where each connections[i] = [city1, city2, cost] represents the cost to connect city1 and city2together.
(A connection is bidirectional: connecting city1 and city2 is the same as connecting city2 and city1.)
This is a companion discussion topic for the original entry at https://algo.monster/problems/min_cost_to_add_new_roads/